Different cities Joomla

I am a project I am about to start.

The client goes to www.website.com then has to pick a city.

The cities are broken down into subdomains:
city1.website.com
city2.website.com
city3.website.com
city4.website.com

Now I would like to have just ONE install of joomla so a user can jump across different cities while still mainting their login status.

I also plan on using community builder, an event script, and a directory script, Gallery2, and possibly a Bulletin board. The user needs to be able to stay logged into all of these sections and those sections also need to have an indivdual gallery, directory, etc for each city but can they all share one joomla installtion... can this be done? and if so how do I plan it out? Also if you are VERY VERY well versed in Joomla I would consider bringing you on board to this project as a consultant because I right now have about ten cities i need to include on this project and many more coming up.

Thanks and i await your response.